diff --git a/src/Dockerfile/Arg.php b/src/Dockerfile/Arg.php
index 5035f5b..2f8fcd6 100644
--- a/src/Dockerfile/Arg.php
+++ b/src/Dockerfile/Arg.php
@@ -8,11 +8,12 @@
 {
     public function __construct(
         private string $name,
+        private string $defaultValue,
     ) {
     }
 
     public function __toString(): string
     {
-        return sprintf('ARG %s', $this->name);
+        return sprintf('ARG %s=%s', $this->name, $this->defaultValue);
     }
 }
diff --git a/src/PHP/ComposerConfig.php b/src/PHP/ComposerConfigGlobal.php
similarity index 84%
rename from src/PHP/ComposerConfig.php
rename to src/PHP/ComposerConfigGlobal.php
index d835195..19f8967 100644
--- a/src/PHP/ComposerConfig.php
+++ b/src/PHP/ComposerConfigGlobal.php
@@ -6,7 +6,7 @@
 
 use Kiboko\Component\Dockerfile\Dockerfile;
 
-final readonly class ComposerConfig implements Dockerfile\LayerInterface, \Stringable
+final readonly class ComposerConfigGlobal implements Dockerfile\LayerInterface, \Stringable
 {
     public function __construct(
         private string $host,